Automatic choke testing method

ABSTRACT

A vortex generator is connected to the automatic choke thermostatic spring housing in place of the usual exhaust manifold heat riser tube, which is disconnected for the first portion of the test. The generator supplies very cold air to the choke housing to immediately simulate cold weather operation and rotate the choke and cooperating operating mechanism to a closed position. The cold source of air is then disconnected and either the hot source of air from the vortex generator then applied to open the choke, at which time the operation can be checked, or the choke is permitted to warm under the prevailing ambient temperature conditions. The simulated cold weather warm-up operation permits an accurate check of operation of all the choke components, that is, the fast idle cam, dechoke and piston pulldown mechanisms, and correlation of choke opening with winding and unwinding of the thermostatic choke coil.

United States Patent [1 1 Hughes et al.

[ AUTOMATIC CHOKE TESTING METHOD [75] Inventors: James R. Hughes,Windsor, Ontario,

Canada; John H. St. John, Birmingham, Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Nov. 3, 1972 [21] Appl. No.: 303,557

[52] US. Cl. 73/118 [51] Int. Cl. G01m 15/00 [58] Field of Search73/118, 1 F; 123/119 F [56] References Cited UNITED STATES PATENTS6/1954 Olson 1 73/1 FX 1/1956 Greer 73/1 F Primary Examiner.lerry W.Myracle Attorney, Agent, or Firm--Robert E. McCollum; Keith L.Zerschling 1 May 7,1974

[57] ABSTRACT A vortex generator is connected to the automatic chokethermostatic spring housing in place of the usual exhaust manifold heatriser tube, which is disconnected for the first portion of the test. Thegenerator supplies very cold air to the choke housing to immediatelysimulate cold weather operation and rotate the choke and cooperatingoperating mechanism to a closed position. The cold source of air is thendiscon- 7 Claims, 7 Drawing Figures PA'TENTEBIAY 7 I974 sum 1 or 2 I 1AUTOMATIC CHOKE TESTING METHOD This invention relates, in general, to anautomatic choke for use with an engine mounted carburetor. Moreparticularly, it relates to a choke testerand a procedure for checkingthe operativeness and accuracy of operation of an automatic chokewithout alteration of the choke structure or removal of the choke fromthe carburetor.

Because an automobile engine is designed and tuned for normal operationat an elevated temperature, some auxiliary control of the air/fuelmixture and fuel metering is required for proper idling performanceduring the very important to the smooth, efficient performance of anautomobile engine.

As an illustration of automatic choke performance, consider theoperation of a typical automatic choke in use today. On a cold engine,the choke plate will initially be firmly closed by a bimetallic coiledspring temperature sensor in the choke housing. When the engine isstarted, the vacuum in the intake manifold pulls downward on a piston toopen the choke plate to a specific opening. No matter how cold theengine, this mechanism exerts sufficient force to overcome thebimetallic coil and open the butterfly valve slightly. Without thisinitial choke operation, the engine would not receive enough air to run.

As the engine warms, the exhaust manifold heats engine compartment airpassing through a shroud or stove surrounding the manifold. This air iscontinuously pulled into the choke housing by the manifold vacuumthrough a heatriser tube. Gradually, the bimetallic coil is warmed. itexpands with increasing temperature and increases the chokeplate-opening by allowing air to move open the choke plate or valve.

- The fast idle cam is also attached to the choke shaft and rotates withthe choke plate. This action controls the minimum throttle opening indiscrete steps to provide the proper fuel delivery rates correspondingto the choke plate opening under any particular idling condition.

A dechoke mechanism is required for opening wide the choke valve byoverriding the normal choke operation when a large quantity of air isrequired to accommodate large throttle openings. This device is simply amechanical linkage between the throttle and the choke shaft. The dechokeis only engaged and actuated by the large throttle motion. When such amotion occurs, the choke plate is forced open to a particular positionproviding the proper dechoke clearance.

Currently, the performance survey of an automatic choke is a ratherhit-or-miss procedure. As a result, the choke mechanism usually receivesattention only when severe and obvious malfunctions occur. The chokeseldom undergoes a routine inspection to insure satisfactoryperformance. However, the need for a relatively simple, quick andefficient device for analyzing and assessing choke performance hasbecome pre-eminent.

The development of a reliable choke testing device would serve twoimportant functions. It would .supplement the capability available inautomotive diagnostic centers as well as improve the ability of amechanic to locate and'repair faulty components in a malfunctioningchoke.

A primary object of the invention, therefore, is to provide a test unitand diagnostic routine for comparing automatic choke performance withdesign requirements under simulated operating conditions.

The automatic choke tester of the invention facilitates chokeperformance analyses by rapidly duplicating the natural ambientconditions of temperature and pressure which are encounteredduring'choke operation. It cools the choke to begin the test sequenceunder simulated cold engine conditions, irrespective of actual enginetemperature. With the choke cool, examinations can be made of thepulldown mechanism performance, dechoke operation, and the fast idle camposition. The choke ,tester then may be used to apply heat to the chokeassembly. At a certain preselected temperature level, the tester canregulate the choke temperature at a constant value while measurementsare made of the choke plate angle and fast idle cam position.

To accomplish the above, the invention employs a high velocity vortexgenerator to separate an incoming compressed air stream into hot andcold outlets. In one embodiment, two valves are used, an inlet valveregulating the total flow rate from the compressed air line through thevortex generator, and a hot outlet valve adjusted to obtain optimum hotor cold outlet temperatures. The hot and cold outlets are alternatelyconnected to the choke heater tube inlet. In another embodiment, onlyone sleeve valve is needed.

A further object of the invention, therefore, is to provide an automaticchoke tester and methodof testing an automatic choke that utilizes avortex generator to separate a source of compressed air into colder andhotter fractions, apply the colder and hotter fractions alternately tothe choketo quickly cool the choke and- /or subsequently warm it fasterthan it would be warmed by the engine ambient temperature alone so thatall of the various functions and operations of the choke structure canbe checked for operativeness an accuracy of operation."

Other objects, advantages and features of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawings thereof; wherein;

FIG. 1 illustrates somewhat schematically a crosssectional view of acarburetor having an automatic choke connected to the tester embodyingthe invention;

FIGS. la and lb are enlarged schematic crosssectionalviews taken,respectively, on planes indicated by and viewed in the directions of thearrows lala and lblb of FIG. 1;

FIG. 2 is a side elevational view of a modified form v of the vortexgenerator shown in FIG. 1;

F16. 2a is an enlarged cross-sectional view of the FIG. 2 construction;

illustrating the preferred embodiments FIG. 2b is a cross-sectional viewtaken on the plane indicated by and viewed in the direction of thearrows 2b-2b of FIG. 2a; and,

FIG. 20 is an enlarged cross-sectional view taken on I a plane indicatedby and viewed in the direction of the arrows 2c2c of FIG. 2a.

FIG. 1 is a cross-sectional view obtained by passing a plane throughapproximately one-half of a known type of four barrel, downdraft typecarburetor. The portion of the carburetor shown includes an upper airhorn section 12, an intermediate main body portion 14, and a throttlevalve flange section 16. Thethree carburetor sections are securedtogether by suitable means, not shown, over an intake manifold indicatedpartially at 18 leading to the engine combustion chambers.

Main body portion 14 contains the usual air-fuel mixture inductionpassages 20 having fresh air intakes at the air horn ends, and connectedto manifold 18 at the opposite ends. The passages are each formed with amain venturi section 22 containing a booster venturi 24 suitably mountedfor cooperation therewith, by means not shown.

Air flow through passages 20 is controlled in part by a choke valve 28fixedly mounted on a shaft 30 rotatably mounted on side portions of thecarburetor air horn, as shown. Flow of fuel and air through each passage20 is controlled by a conventional throttle valve 36 fixed to a shaft 38rotatably mounted in flange portion 16. The throttle valves are rotatedin a known manner by depression of the vehicle accelerator pedal, andmove from an idle speed position essentially blocking flow throughpassage 20 to a wide open position essentially at right angles to theposition shown.

The rotative position of choke valve 28 is controlled in a known mannerby a semi-automatically operating choke mechanism 40. The latterincludes a hollow housing portion 42 that is formed as an extension ofthe carburetor throttle flange. The housing is apertured for supportingrotatably one end of a choke lever operating shaft 44, the opposite endbeing rotatably supported in a casting 46. A bracket or lever portion 48is fixed on the left end portion of shaft 44 for mounting the end of arod 52 that is pivoted to choke valve shaft 30. It will be clear thatrotation of shaft 44 in either direction will correspondingly rotatechoke valve 28 to open or close the carburetor air intake, as the casemay be.

An essentially L-shaped thermostatic spring lever 54 has one leg 56fixedly secured to the opposite or righthand end portion of shaft 44.The other leg portion 58 of the lever is secured to the end 59 of acoiled thermostatic spring element 60. The opposite end portion 62 ofthe spring is fixedly secured on the end of a nipple 64 that is formedas an integral portion of a choke cap 66 of heat insulating material.Nipple 64 is bored as shown to provide hot air passages 68 and 70,passage 68 being connected to an exhaust manifold heat stove, forexample. Cap 66 is secured to housing 42 by suitable means, such as thescrew 72 shown, and defines an air or fluid chamber 74 within the two.

As thus far described, it will be clear that the thermostatic springelement 60 will contract or expand as a function of the changes inambient temperature conditions of the air entering tube 68, or, if thereis no flow, the temperature of the air within chamber 74. Accordingly,changes in ambient temperature will rotate the spring lever 54 to rotateshaft 44 and choke valve 28 in one or the other directions, as the casemay be.

The leg 56 of spring lever 54 is pivotally fixed to the rod 76 of apiston 78. The latter is movably mounted in a bore 79 in housing 42. Theunder surface of piston 78 is acted upon by vacuum in a passage 80 thatis connected to the carburetor main induction passages 20 by a port 82that is located just slightly below throttle valve 36. Piston 78,therefore, is always subject to the vacuum existing in the intakemanifold passage portion 18.

As is known, a cold weather start of a motor vehicle requires a richermixture than a warmed engine start because considerably less fuel isvaporized; Therefore, the choke valve is shut or nearly shut to admitless air. Once the engine does start, however, then the choke valveshould be opened slightly to lean the mixture to prevent engine floodingas a result of an excess of fuel.

The known choke mechanisms described automatically accomplish the actiondescribed. That is, on cold weather starts, the temperature of the airin chamber 74 will be low so that spring element will contract androtate shaft 44 and choke valve 28 to a closed or nearly closedposition, as desired. Upon cranking the engine, vacuum in passage willnot be sufficient to move piston 78 to open the choke valve.Accordingly, the engine will be started with a rich mixture. As soon asthe engine is running, high vacuum in passage 80 now moves piston 78downwardly and rotates shaft 44 a slight amount so that choke valve 28is slightly openedto admit more air to induction passage 20. Shortlythereafter, the exhaust manifold stove air in line 68 will becomeprogressively warmer and cause choke element 60 to unwind and rotateshaft 44.and choke valve 28 to a more open position. 84 represents aconventional fast idle cam fixed on choke shaft 44. It would include acylindrical hub with a stepped cam face projecting radially from oneside, and a weighted lever segment projecting from the opposite side.The weighted lever would cooperate with a throttle stop or screw (notshown) adjustably mounted on a lever (also not shown) that would befixed to throttle valve shaft 38. The end of the screw would be biasedby the throttle valve return spring against the stepped cam face of thefast idle cam during idle to control the idle speedposition of thethrottle valve. As the temperature increased, the coil'60 would rotatethe fast idle cam to position other lesser steps in the path of thethrottle shaft screw, to progressively decrease idle speed until itreached the normal level at normal engine operating temperature.

Further details of construction and operation are not given since theyare known and believed to be unnecessary for an understanding of theinvention.

As stated previously, to test the automatic choke operation for accuracyof performance and operability, the passage 68 leading to choke chamber74 is adapted to be connected to a source of cold air to simulate coldoperation of the choke even though the engine operating temperatures andambient temperatures surrounding the choke normally would not conditionthe choke for cold operation. The passage 68, in this case, is shownconnected to a flexible tube 68a. This tube nor-v mally would beconnected to the exhaust manifold heat stove, but to test the chokewould be reconnected to the cold outlet of a vortex generator 92.

In general, the vortex generator per se could be ofa known type similarto that shown and described in U.S.

Pat. No. 2,581,168, A. Bramley. More specifically, the vortex generatorincludes a cylindrical vortex chamber 94 of a predetermined diameterhaving a tangential air inlet 96 (FIGS. la and lb). The inlet receivescompressed air therein from any suitable source, not shown. Thecompressed air would be controlled by an on-off valve 98.

As best seen in FIG. 1, the vortex generator has two axial outlets ofdiffering diameters smaller than the diameter of the vortex chamber.Cold air flows from the vortex chamber 94 through the smaller outlettube 90, while the hotter air flows axially in the opposite directionthrough the larger diameter tube 100. An on-off progressive controlvalve 102 of a known type may be used to control the hot outlet 100.

The vortex generator operates in a known manner as fully described inthe Bramely patent. In brief, compressed air enters vortex chamber 94 ina tangential direction to swirl centrifugally therein and separate theflow into colder and hotter fractions. The colder portion flowsalongthe, axis through the smaller diameter tube 90 to the choke housingtube 68a, while the hotter fraction flows peripherally along the wallsof the larger tube 100 in the opposite direction past the valve 102.Adjustment of valve 102 to restrict or permit freer outlet of the hotair controls the proportion of hot to cold sources of air.

When it is desired to test the choke 40 for operativeness and accuracyof operativeness, under cold weather simulated conditions, the flexibletube 68a emanating from the choke will be disconnected from the en gineexhaust manifold heat stove, not shown, and connected to the cold outlet90 of the vortex generator 92, as shown. Immediately, the air in chamber74 of the choke 40 will become quite cold, in the neighborhood of 0F.,or less, for example. This will immediately cause the thermostaticspring 60 to contract and rotate the choke valve 28 to a closed positionto simulate cold weather operating conditions even though the ambienttemperature around the choke may belquite high.

Once the choke valve has been rotated to the closed position, the tube68a then can be disconnected from the choke and either again connectedto the exhaust manifold heat stove to again apply engine heat, or keptdisconnected and the choke chamber 74 allowed to slowly rise to ambienttemperature conditions. Alternatively, the tube 68a can be connected tothe hot outlet end 100 of the vortex generator 92 so that thetemperature conditions in chamber 74 of the choke can be brought back towarm engine operating conditions.

Under any of the conditions outlined above, initially, when the chokevalve is closed, the positions of the fast idle cam 84 can be checkedfor accuracy of position, the pulldown piston 78 can be operated againstthe tension of spring 60 to check the initial opening of the chokevalve, and the dechoking mechanism, not shown, can be operatedto seethat it is satisfactory.

For all of the above operations, as the thermostatic spring 60 issubjected to the warmer air, it progressively unwinds and, therefore,slowly rotates the choke valve 28 in a progressive manner to an openposition. During this time, the degree of opening of the choke valvewith changes in temperature can be checked for correlation to see if thechoke is operating correctly.

It will be seen from the above, therefore, that the invention provides asimple procedure for checking the cold operation of a chokeundersimulated cold weather operating conditions regardless of the actualambient and engine operating temperatures. The invention can provide asource of very cold air, for example 50F., or a much hotter temperature,for example, 250F., that can be quickly connected to the choke housingto simulate both temperature and pressure conditions of the choke underboth cold and hot engine operating conditions.

FIG. 2 illustrates a modified construction of the vortex generator shownin FIG. 1. More particular, FIG. 2 shows a sleeve valve typeconstruction requiring only a single outlet instead of the dual hot-coldoutlets of the vortex generator shown in FIG. 1. The FIG. 2 constructionalternates the discharge of hot or cold air merely by rotating thesleeve valve. to its various operative positions. It also includes avent position in which neither hot nor cold air is connected to theoutlet, but both are vented to the atmosphere.

' More specifically, FIGS. 2a, 2b and 20 show the detailedconstructionof the vortex generator. It consists of a stepped diametermain body on which is slidably mounted a sleeve 112. The sleeve containsa pair of throughports 114 interconnected by a passage 116. A thirdthroughport 118 is fitted to an adapter 120 and constitutes the mainoutlet of the vortex generator. The port 118 is connected by a transferconduit 122 to an internal port 124.

The stem end 126 of main body portion 110 contains a recess or bore 128that threadedly receives an air compressor inlet fitting 130. Moreparticularly, a hollow adapter 132 would be connected at one end 134 toa suitable source of compressed air, not shown. Its other end isreceived in the recess 135 of aplug having an angled passage 136connecting the recess to the outer peripheral portion 138 of an annularchamber 140. The chamber contains a vortex generator 92 consisting ofadisc 142 (FIG. 20) having a plurality of equally circumferentiallyspaced tangential inlets 144 for the passage of air in inclined passage136 inwardly into an annular vortex chamber 146 in a manner similar tothat described in connection with the FIG. 1 embodiment 94.

The vortex generator in this case is fixed to a larger diameter disc 148having a central opening 150 and formed integrally with a tube 152. Thetube 152 extends through a multi-diameter opening 154 in the right handend of main body member 1 10 to a point adjacent the opposite end, whichis closed by a plug 156. A second tube 158 surrounds tube 152, whichterminates slightly short of the end of tube 158. This is so any air intube 152 will flow out of and around the end 160 of the tube and throughthe passage 161 formed between tubes 158 and 152. A pair of differentdiameter passages 162 and 164 connect with the passage 162 and each passoutwardly to the sleeve 1 12, for a purpose to be described.

Returning now to the vortex generator, the outer chamber 140 is sealedby an annular rubber or elastomer ring 167 that is assembled between thedisc 148 and the inner end of the plug 130. This causes all incomingcompressed air in inclined passage 136to be confined within the annularpassage 140 for passage tangentially into vortex chamber 146 through theinlets 144. The plug 130 also contains an axial bore 170 that has aradial connection 172 to a cooperating port 174. The port opens to theouter periphery of the main body portion and contains a phenolic orplastic plug 176.

The plug has a predetermined diameter cold air outlet opening 178communicating with the interior of vortex chamber 146.

It will be seen, like the construction shown in FIG. 1,

that the vortex chamber has two outlets of different diameters and eachof a smaller diameter than the vortex chamber 146 for passage of hot andcold air from the vortex generator through the tubes 152 and bore 170,respectively,

In operation, the main outlet 120 is adapted to be connected alternatelyto the source of colder air in bore 170 by way of passages 174 and 122,or to the hotter air source in tube 152 and passage 161 through theconnecting conduit 164. Alternatively, both the hot and cold sources canbe vented to atmosphere by connection through a vent 180 shown in FIG.2b.

The lower portion of the sleeve 112 is provided with an arcuate groove178 that slidably receives'a pin 179 fixed in a hole in the main bodyportion 110. As best 2a and 2b. The source of cold air in bore 170 willpass directly to the vent openings 114, while the smaller diameter hotconduit 162 will be connected to the main outlet 120, as shown. Thelarger diameter outlet 164 at this time will be blocked by being at anangular position out-of-line with both the outlet I and the vent 114.

When the sleeve 112 is rotated to align the arrow 186 with theventposition, the vent 180 shown in FIG. 2b will be aligned with thecold outlet port 174, and the hot outlets will both be blocked.

When the sleeve valve is rotated so that the indicator 186 is alignedwith the cold position, the cold outlet port 174 will be aligned withthe internal port 124 so that the cold air will pass directly to themain outlet 120. At this time, the hot, larger diametered conduitl64will be connected to the vent port 114, while the smaller passage 162will be blocked. I

From the foregoing, it will be seen that the FIG. 2 embodiment providesa single valve that alternately connects the hotter or colder source tothe single outlet 120. Therefore, merely by rotating the sleeve 112, thechoke 40 can be subjected alternately to cold or hotter sources of air.

From the foregoing, it will be seen that the invention provides a quickand accurate method as well as structure for accurately checking theperformance of an automatic choke under simulated cold or hot weatheroperating conditions.

We claim:

1. A method of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletype automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbal- 'ance mounted, air movablechoke valve for urging the same towards a position closing the upper endof a carburetor induction passage in response to decreases intemperature level below a predetermined level and movable to a positionopening the induction passage in response to airflow thereagainstthrough the passage, the method including connecting a source ofcompressed air at a given temperature level to the outer peripheraltangential inlet of a vortex generator to divide the flow into a sourceof colder air flowing along the axis and a source of hotter air flowingaxially radially outwardly of the colder source; connecting the colderair source to the choke at an area adjacent the temperature responsivemeans sufficient for it to close the choke valve regardless of engineoperating temperatures adjacent the choke; and, disconnecting the colderair source from the choke and checking the operation and angle ofprogressive'opening of the choke as the temperature responsive meansagain is subjected to warmer temperature conditions.

2. A method as in claim 1, including the steps of connecting the warmerair source from the vortex generator to the temperature responsive meansto apply heat to the temperature responsive means to warm it faster thanif subject to engine temperatures alone, until a preselected level isreached.

3. A method of quickly'checking, in place and regardless of engine andambient temperature conditions,

the operativeness of a motor vehicle type automatic choke having ahousing enclosing a temperature responsive member operatively connectedto an unbalance mounted, air movable choke valve for urging the responseto airflow thereagainst through the passage,

and also having a choke pulldown means operatively connected to thechoke valve and operative upon engine startup to override the force ofthe temperature responsive means to crack open the chokevalve apredetermined amount; the method including; connecting a source ofcompressed air at a given temperature level to the outer peripheraltangential inlet of a vortex generator to divide the flow into a sourceof colder air flowing along the axis and a source of hotter air flowingaxially radially outwardly of the colder source, connecting the colderair source to the choke to an area adjacent the temperature responsivemeans to cool the temperature responsivemeans sufficient for it to closethe choke valve, checking the operation of the choke pulldown mechanismby operating the same in opposition to the force of the cooledtemperature responsive means, disconnecting the colder air source fromthe choke and connecting the warmer air source thereto to apply heat tothe temperature responsive means until a preselected level is reached;and, operating valve means on the vortex generator controlling theoutput of one of the sources to vary the proportion of flow from thesources to maintain the temperature level at the preselected level whilechecking the choke plate angle.

4. A method of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletupe automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbalance mounted, air movable chokevalve for urging the same towards a position closing the upper end of acarburetor induction passage in response to decreases in temperaturelevel below a predetermined level and movable to a position opening theinduction passage in response to airflow thereagainst through thepassage, and having an open throttle dechoking mechanism and a fast idlecam movable with the choke valve and having steps cooperating with anadjustable stop secured to the throttle valve to provide a number offast idle speed settings; the method including connecting a source ofcompressed air at a given temperature level to the outer peripheraltangential inlet of a vortex generator to divide the flow into a sourceof colder air flowing along the axis and a source of hotter air flowingaxially radially outwardly of the colder air source to the choke to anarea adjacent the temperature responsive means to cool the temperatureresponsive means sufficient for it to close the choke valve regardlessof warmer engine operating temperatures, checking the dechokingmechanism and the position of the fast idle cam by opening and closingthe carburetor throttle valve; and disconnecting the colder air sourcefrom the tube inlet and checking the operation and angle of progressiveopening of the choke as the temperature responsive means again issubjected to warmer temperature conditions.

5. A method as in claim 4, including the steps of connecting the warmerair source to the choke housing to apply heat to the temperatureresponsive means until a preselected level is reached; and, operatingvalve means on the vortex generator controlling the output of one of thesources to vary the proportion of flow from the sources to maintain thetemperature level at the preselected level while concurrently checkingthe choke plate angle and fast idle cam-position.

6. A method of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletype automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbalance mounted, air movable chokevalve for urging the same towards a position closing the upper end of acarburetor induction passage in response to decreases in temperaturelevel below a predetermined level and movable to a position opening theinduction passage in response to airflow thereagainst through thepassage, and also having a choke pulldown means operatively connected tothe choke valve and operative upon engine startup to override the forceof the temperature responsive means to crack open the choke valve apredetermined amount, and having a tube connecting engine exhaustmanifold heated air through the choke housing to the interior adjacentthe temperature responsive means, and a fast idle cam movable with thechoke valve and having steps cooperating with an adjustable stop securedto the throttle valve, and an open throttle dechoking mechanism; themethod including connecting a source of compressed air at.a giventemperature level to the outer peripheral tangential inlet of a vortexgenerator to divide the flow into a source of colder air flowing alongthe axis and a source of hotter air flowing axially radially outwardlyof the colder sourc; connecting the colder air source to the choke to anarea adjacent the temperature responsive means to cool the temperatureresponsive means sufficient for it to close the choke valve regardlessof warmer engine operating temperatures, and, checking the operation ofthe choke pulldown mechanism by operating the same in opposition to theforce of the cooled temperature responsive means, and checking theposition of the fast idle cam and performance dechoking mechanism byopening and closing the carburetor throttle valve; disconnecting thecolder air source from the tube inlet and reconnecting the heated airtube thereto, and again checking the opening degrees of movement of thechoke valve as the temperature responsive means is again subjected tothe warmer engine exhaust manifold heat reducing the bias of thetemperature responsive means.

7 The method of claim 6 including connectingthe warmer air source of thevortex generator to the heated air tube housing inlet in place of theheated air tube when the colder air source is disconnected therefrom.

1. A method of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletype automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbalance mounted, air movable chokevalve for urging the same towards a position closing the upper end of acarburetor induction passage in response to decreases in temperaturelevel below a predetermined level and movable to a position opening theinduction passage in response to airflow thereagainst through thepassage, the method including connecting a source of compressed air at agiven temperature level to the outer peripheral tangential inlet of avortex generator to divide the flow into a source of colder air flowingalong the axis and a source of hotter air flowing axially radiallyoutwardly of the colder source; connecting the colder air source to thechoke at an area adjacent the temperature responsive means sufficientfor it to close the choke valve regardless of engine operatingtemperatures adjacent the choke; and, disconnecting the colder airsource from the choke and checking the operation and angle ofprogressive opening of the choke as the temperature responsive meansagain is subjected to warmer temperature conditions.
 2. A method as inclaim 1, including the steps of connecting the warmer air source fromthe vortex generator to the temperature responsive means to apply heatto the temperature responsive means to warm it faster than if subject toengine temperatures alone, until a preselected level is reached.
 3. Amethod of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletype automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbalance mounted, air movable chokevalve for urging the same towards a position closing the upper end of acarburetor induction passage in response to decreases in temperaturelevel below a predetermined level and movable to a position opening theinduction passage in response to airflow thereagainst through thepassage, and also having a choke pulldown means operatively connected tothe choke valve and operative upon engine startup to override the forceof the temperature responsive means to crack open the choke valve apredetermined amount; the method including; connecting a source ofcompressed air at a given temperature level to the outer peripheraltangential inlet of a vortex generator to divide the flow into a sourceof colder air flowing along the axis and a source of hotter air flowingaxially radially outwardly of the colder source, connecting the colderair source to the choke to an area adjacent the temperature responsivemeans to cool the temperature responsive means sufficient for it toclose the choke valve, checking the operation of the choke pulldownmechanism by operating the same in opposition to the force of the cooledtemperature responsive means, disconnecting the colder air source fromthe choke and connectinG the warmer air source thereto to apply heat tothe temperature responsive means until a preselected level is reached;and, operating valve means on the vortex generator controlling theoutput of one of the sources to vary the proportion of flow from thesources to maintain the temperature level at the preselected level whilechecking the choke plate angle.
 4. A method of quickly checking, inplace and regardless of engine and ambient temperature conditions, theoperativeness of a motor vehicle tupe automatic choke having a housingenclosing a temperature responsive member operatively connected to anunbalance mounted, air movable choke valve for urging the same towards aposition closing the upper end of a carburetor induction passage inresponse to decreases in temperature level below a predetermined leveland movable to a position opening the induction passage in response toairflow thereagainst through the passage, and having an open throttledechoking mechanism and a fast idle cam movable with the choke valve andhaving steps cooperating with an adjustable stop secured to the throttlevalve to provide a number of fast idle speed settings; the methodincluding connecting a source of compressed air at a given temperaturelevel to the outer peripheral tangential inlet of a vortex generator todivide the flow into a source of colder air flowing along the axis and asource of hotter air flowing axially radially outwardly of the colderair source to the choke to an area adjacent the temperature responsivemeans to cool the temperature responsive means sufficient for it toclose the choke valve regardless of warmer engine operatingtemperatures, checking the dechoking mechanism and the position of thefast idle cam by opening and closing the carburetor throttle valve; anddisconnecting the colder air source from the tube inlet and checking theoperation and angle of progressive opening of the choke as thetemperature responsive means again is subjected to warmer temperatureconditions.
 5. A method as in claim 4, including the steps of connectingthe warmer air source to the choke housing to apply heat to thetemperature responsive means until a preselected level is reached; and,operating valve means on the vortex generator controlling the output ofone of the sources to vary the proportion of flow from the sources tomaintain the temperature level at the preselected level whileconcurrently checking the choke plate angle and fast idle cam position.6. A method of quickly checking, in place and regardless of engine andambient temperature conditions, the operativeness of a motor vehicletype automatic choke having a housing enclosing a temperature responsivemember operatively connected to an unbalance mounted, air movable chokevalve for urging the same towards a position closing the upper end of acarburetor induction passage in response to decreases in temperaturelevel below a predetermined level and movable to a position opening theinduction passage in response to airflow thereagainst through thepassage, and also having a choke pulldown means operatively connected tothe choke valve and operative upon engine startup to override the forceof the temperature responsive means to crack open the choke valve apredetermined amount, and having a tube connecting engine exhaustmanifold heated air through the choke housing to the interior adjacentthe temperature responsive means, and a fast idle cam movable with thechoke valve and having steps cooperating with an adjustable stop securedto the throttle valve, and an open throttle dechoking mechanism; themethod including connecting a source of compressed air at a giventemperature level to the outer peripheral tangential inlet of a vortexgenerator to divide the flow into a source of colder air flowing alongthe axis and a source of hotter air flowing axially radially outwardlyof the colder sourc; connecting the colder air source to the choke to anarea adjacent the temperature responsive means to cool the temperatuReresponsive means sufficient for it to close the choke valve regardlessof warmer engine operating temperatures, and, checking the operation ofthe choke pulldown mechanism by operating the same in opposition to theforce of the cooled temperature responsive means, and checking theposition of the fast idle cam and performance dechoking mechanism byopening and closing the carburetor throttle valve; disconnecting thecolder air source from the tube inlet and reconnecting the heated airtube thereto, and again checking the opening degrees of movement of thechoke valve as the temperature responsive means is again subjected tothe warmer engine exhaust manifold heat reducing the bias of thetemperature responsive means.
 7. The method of claim 6 includingconnecting the warmer air source of the vortex generator to the heatedair tube housing inlet in place of the heated air tube when the colderair source is disconnected therefrom.